Mouth guard formation methods

ABSTRACT

A method for producing a mouth guard having an encapsulated sensor module. The method includes vacuum forming a first sheet of thermoplastic material using a mold to produce a first mouth guard layer, attaching a sensor module to the first mouth guard layer with a hot melt adhesive, vacuum forming a second sheet of thermoplastic material over the sensor module to produce a second mouth guard layer, storing a default threshold level in the sensor module, and calibrating the sensor module to account for sensor alignment. In an example embodiment, the first and second layers are formed such that they define an open area that allows a user&#39;s tongue to touch their upper palate after the mouth guard has been inserted and such that the layers define a channel for accepting a plurality of teeth, including the incisors of a user.

PRIORITY CLAIM

This application claims the benefit of U.S. Provisional Application Ser. No. 61/336,429 filed Jan. 22, 2010 and U.S. Provisional Application Ser. No. 61/409,906 filed Nov. 3, 2010, the contents of both are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

Participation in athletic activities is increasing at all age levels. All participants may be potentially exposed to physical harm as a result of such participation. Physical harm is more likely to occur in athletic events where collisions between participants frequently occur (e.g., football, field hockey, lacrosse, ice hockey, soccer and the like). In connection with sports such as football, hockey and lacrosse where deliberate collisions between participants occur, the potential for physical harm and/or injury is greatly enhanced. Approximately 300,000 athletes incur concussions in the United States each year. This may be a conservative estimate because many minor head injuries go unreported. Although most concussions occur in high-impact sports, athletes in low-impact sports are not immune to mild traumatic brain injury. Head injuries are caused by positive and negative acceleration forces experienced by the brain and may result from linear or rotational accelerations (or both). Both linear and rotational accelerations are likely to be encountered by the head at impact, damaging neural and vascular elements of the brain.

At the school level, school authorities have become sensitive to the risk of injury to which student participants are exposed, as well as to the liability of the school system when injury results. Greater emphasis is being placed on proper training and instruction to limit potential injuries. Some players engage in reckless behavior on the athletic field or do not appreciate the dangers to which they and others are subject by certain types of impacts experienced in these athletic endeavors. Unfortunately, the use of mouth guards and helmets does not prevent all injuries. One particularly troublesome problem is when a student athlete experiences a head injury, such as a concussion, of undetermined severity even when wearing protective headgear. Physicians, trainers, and coaches utilize standard neurological examinations and cognitive questioning to determine the relative severity of the impact and its effect on the athlete. Return to play decisions can be strongly influenced by parents and coaches who want a star player back on the field.

The same problem arises in professional sports where the stakes are much higher for a team, where such a team loses a valuable player due to the possibility of a severe head injury. Recent medical data suggests that lateral and rotational forces applied to the head and neck area (for example, flexion/extension, lateral flexion, and axial rotation) are more responsible for axonal nerve damage than previously thought. Previous medical research had indicated that axially directed forces (such as spinal compression forces) were primarily responsible for such injuries.

Identifying the magnitude of acceleration that causes brain injury may assist in prevention, diagnosis, and return-to-play decisions. Most field measurements assess the acceleration experienced by the player with accelerometers attached to the helmet. The following show some attempts for measuring the impacts to the skull and brain while the player is participating in a sporting activity. U.S. Pat. No. 5,539,935, entitled “Sports Helmet,” issued on Jul. 30, 1996 and U.S. Pat. No. 5,621,922, entitled “Sports Helmet Capable of Sensing Linear and Rotational Forces,” issued on Apr. 22, 1997 are examples of some of those attempts. Both patents relate to impact sensors for linear and rotational forces in a football helmet. These devices test the impact to the skull of a player. If an athlete suffers a concussion, for example, it will be possible to determine if the relative magnitude of an impact is dangerously high relative to a threshold to which each sensing device is adjusted, taking into consideration the size and weight of the player.

Another attempt performs testing impact acceleration to the head with an intraoral device which provides acceleration information of the brain in various sports. Other attempts have been made, however all these attempts can be costly to implement and fail to provide full historical medical information to coaches, trainers and medical professionals in real-time for dozens of players at a time on one or more adjacent fields.

SUMMARY OF THE INVENTION

The present invention provides a wirelessly linked sports impact sensing and reporting system. The system mainly includes one or more player electronics modules, a sideline module, and a remotely served and remotely accessible recording database module. In one aspect of the invention, the player module is housed independently within the volume of a set of an otherwise standard mouth guard and chin strap assembly, the sideline module is housed within the structure of an otherwise standard clipboard, and the database module is accessible via a network, e.g., public or private Internet.

In one version of the invention, the player module includes a plurality of sensors capable of detecting impact events in multiple axes, a battery, a data memory storage device, a microprocessor and a LED status indicator array. Each player module includes an RF transducer module and an antenna system, capable of establishing a wireless mesh network for reporting the data associated with an impact to the player. A zinc-air primary cell battery is used with the present player module device, but may be substituted by use of a lithium-polymer rechargeable battery or similar.

In another version of the invention, the sideline module includes a radio system capable of acting as a node on the wireless network and receiving signals from any of the player modules participating on the wireless mesh network in real-time. The sideline module also includes a battery, a data memory storage device, a microprocessor and a display capable of indicating impact information per player on the wireless mesh network, severity of impact, and recommended action in near real-time. The sideline module also includes a loudspeaker capable of generating audible alert tones to attract a coach's attention to incoming information in real-time. A zinc-air primary cell battery is used with the present player module device, but may be substituted by use of a lithium-polymer rechargeable battery or similar.

In still another version of the invention, the database module includes a database of players and associated impact data arrangeable by name, team, date, severity of impact, frequency of impact, and many other parameters. The database module is so constructed to be accessible via the public or private data network and is configured to provide various degrees of access to its information contents. Access accounts may be configured according to individual, team, division, league, physician, and administrator levels. Each account will be granted access to the appropriate set of data only, and password protection will ensure dissemination of data only to authorized parties.

In yet an additional version of the invention, an example system includes a mouth guard having a proximity sensor, an accelerometer, a gyroscope, a processor in signal communication with the accelerometer and gyroscope, a memory in data communication with the processor, a transmitter in signal communication with the processor, and a battery that provides power to the processor, the memory, the accelerometer, and the gyroscope. The processor is configured to allow power from a battery to flow to the accelerometer and gyroscope when the proximity sensor detects that the mouth guard has been inserted into a mouth. The processor is also configured to instruct the transmitter to transmit a signal if an acceleration above a predefined first threshold is sensed and to continue transmitting if an acceleration above a predefined second threshold is sensed before a first time period is complete.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings:

FIG. 1 is a drawing showing an example of the invention in context of a football player's head in profile, while wearing a football helmet and the sensor-enabled mouth guard and chin strap set, i.e. the player module;

FIG. 2 is a drawing showing the player module in context of its positioning as worn within a human head;

FIG. 3 is a drawing in isometric view showing an example mouth guard element of the player module and indicating the positioning of embedded sensor elements and conductors;

FIG. 4 is a drawing in plan view showing the example mouth guard element of the player module and indicating the positioning of embedded sensor elements and conductors;

FIG. 5 is a drawing showing a side view of an example player module, including the mouth guard element and chinstrap element, and showing the relationship and connection between the two;

FIG. 6 is a drawing in isometric view showing the player module, including mouth guard and chinstrap elements;

FIG. 7 is a drawing showing a portion of an example sideline module embodied as a clipboard, with a display and input buttons in the uppermost region;

FIG. 8 illustrates an exemplary system formed in accordance with an embodiment of the present invention;

FIG. 9 is a perspective view of a mouth guard formed in accordance with an embodiment of the invention;

FIG. 10 is a diagram of a sensing module in the mouth guard shown in FIG. 9;

FIG. 11 is a top view of the mouth guard shown in FIG. 9;

FIG. 12 is a front view of the mouth guard shown in FIG. 9;

FIG. 13 is a side view of the mouth guard shown in FIG. 9; and

FIG. 14 is a flowchart of a method of producing a mouth guard having an encapsulated sensor module.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A preferred version of the present invention is a system for the detection, measurement, characterization, transmission, and/or reporting of events causing impact forces to be experienced by players, for example football players. Thus, as shown in FIGS. 1 and 2, a preferred system is configured for use with a mouth guard in a situation in which a player also uses a chinstrap and a helmet. In other examples, various sensors may be incorporated into other housings such as headbands, goggles, or other headgear. The system conveys to an authority figure, preferably a coach or trainer, useful information about the identity of the impacted player, the severity of the impact, and suggested actions for evaluating the condition of the player and for making decisions about the players subsequent status vis-á-vis readiness to return to play or referral to a physician's care.

An example of the player module includes an arrangement of a plurality of low-cost, distributed sensors arranged between the inside surface of the player shell and the bottom surface of a padding elements that provide fit and cushioning to the player's head. These sensors may alternatively be positioned intermediately within the padding element, either at the interface of two laminated elements, or by encapsulation directly within the mass of the padding element. The sensors may also be situated within cavities of the player or in the spaces between padding elements. For example, these sensors may be MEMS type impact sensors, MEMS accelerometers, miniature weighted cantilevers fitted with miniature strain-gauge elements, piezoelectric membranes, or Force-Sensitive-Resistors (FSR).

In one example, the sensors are incorporated into a sensor unit that is configured as a mouth guard. Thus, as shown in FIGS. 3 and 4, various sensors may be encapsulated into the material formed as a mouth guard. In the illustrated version, sensors are shown being positioned at a lower surface of the mouth guard, beneath the channel formed to receive a user's teeth. As also illustrated, the exemplary mouth guard of FIGS. 3 and 4 includes a wire or tether, preferably encapsulated in a protective covering, extending from a forward portion of the mouth guard in order to send data to a base unit or other device. In other versions, as described below, the mouth guard includes an antenna for wirelessly transmitting the data to an intermediate module or directly to a sideline receiving unit.

The sensors employed in the player module are connected electronically by means of wires or printed flex circuitry to an electronics pod or other similar means, in some versions situated within a primary shell of the player, and within the space available between two or more padding elements. As illustrated in FIGS. 5 and 6, in some versions the mouth guard sensors are communicatively coupled to a receiving unit contained within a chin strap or other such component external to the mouth. The chin strap includes electronic components to transmit the data received from the mouth guard and then pass it along to a sideline receiving unit. Most preferably the data is passed along in real time, although in some versions the data is stored in a memory and downloaded at a later time.

The electronics pod (whether in the helmet, the mouth guard, the chin strap, or another location) collects, processes, evaluates, and if appropriate, transmits data pertaining to an impact event via radio to one or more other participant nodes of the wireless network to which the player module belongs. The electronics pod contains electronic circuitry having components such as a microprocessor, flash memory, radio module, antenna, and status display LEDs. In the circuit's memory resides a database lookup table for evaluation of sensor data and comparison to combinations of impact levels that represent suspicious likelihood of Mild Traumatic Brain Injury (MTBI) or concussion. The electronics pod is also configured to monitor, evaluate, and/or display system status information such as link to network, battery charge status, and proper system functioning.

An example sideline module is an electronic data gathering and display device incorporated into a portable enclosure that is easy for a coach, trainer, or other such game official to carry, consult, and interact with during the activities of the practice or game. In one embodiment, the sideline module is embedded into the topmost section of a clipboard, for example as illustrated in FIG. 7. Since the majority of coaches and trainers need to carry clipboards anyway, this is perceived as the most natural and least obtrusive way to provide impact information. However, many other configurations of the sideline module are possible, including building it into a wristband, a stopwatch-style fob with a neck lanyard, a device similar to a mobile phone or pager, etc. The sideline module may be in the form of any electronic receiving device, including laptop computers, mobile phones, or any other such device configurable to receive wireless information. Moreover, the sideline module is described as receiving information directly from the sensor unit, although in some versions of the invention the sensor module may pass its data to an intermediate server or other device which then forwards the information to the sideline module.

The sideline module includes electronic components arranged into a circuit that allows for participation in the wireless mesh network established by a set of player modules, and specifically for the receipt of data transmissions from the player modules, and subsequently the display of impact event information on a visual display in real-time. The sideline module also produces audible and vibratory alert signals to call attention to the arrival of new data messages in real-time, which are disabled by manual conscious intervention of the coach or trainer, indicating acknowledgement of receipt of impact event data.

In one embodiment, the sideline module performs the classification of incoming impact data into one of three categories, indicating differing levels of concern and differing levels of urgency of response. The system employs a “GREEN LIGHT” “YELLOW LIGHT” and “RED LIGHT” system, in which a GREEN LIGHT status indicates the absence of significant impact events for a given player, a YELLOW LIGHT indicates the need for immediate sideline evaluation of the player, and RED LIGHT indicates a severe enough impact that the player be removed from play and referred to a physician immediately.

Upon registering a YELLOW LIGHT impact event, and upon subsequent acknowledgement of receipt of the message by the coach or trainer, the sideline module, in one embodiment, leads the coach or trainer through a simple protocol for evaluation of the player's condition. Through answering a series of simple Yes or No questions, the sideline module guides the coach or trainer to a limited number of possible suggested actions. These potential outcomes could include immediate referral to a physician for further examination, or a period of bench time observation followed by a secondary guided evaluation before allowing the player to return to play.

In one embodiment, a durable record of data transactions is received in real-time and is kept independently of the sideline module or modules. Such a database provides players, parents, coaches, trainers, administrators and other stakeholders access to a record of what impact event information was conveyed, when, to whom and about which player. The sideline module is equipped with a wide area network radio module for transmission of a record of all data transactions on the system with time stamp and a record of the actions by coaches and content of player evaluations. A standard 1 way or 2 way pager system is used, which has the benefit of being inexpensive and nearly ubiquitous in availability throughout much of the world. Alternatives to pager radio systems are cellular radios of various kinds and other wide area network wireless connections. The knowledge that this information will be available to stakeholders provides accountability to all stakeholders in the health and well being of the player.

In one embodiment, the database is populated by an automatic interface to the wide area radio network accessed by the sideline network, and is accessible to stakeholders by means of internet based applications, equipped with password protected hierarchical account structures. The system provides parents the ability to log on to their account and review the totality of impact event data and the record of coach responses associated with their player.

Each player module at the start of each season maps its unique identifier code to a particular player's name and number. It is possible that during the course of events players might accidentally wear the wrong player number and potentially cause confusion by users of the system. It is for this reason that each player module has, in one embodiment, a visual indicator array of LEDs, which will repeatedly flash a visible signal in case of transmission of an impact event of concern. A yellow light flashes to indicate the transmission of a YELLOW LIGHT event, and a red light flashes to indicate the transmission of a RED LIGHT event. When the player is called to the sidelines for evaluation, the coach or trainer can disable the flashing indicator light by simultaneously depressing a button on the player module and a button on the sideline module. This provides positive confirmation that the player who sustained the reported impact is in fact the player being evaluated by the coach or trainer.

FIG. 8 illustrates an exemplary system 100 that performs aggregation of head-acceleration information received from a plurality of sensor units 102 and makes the acceleration information available to relevant parties. The sensor units are the mouth guards or other components as described above that incorporate one or more sensors. The system 100 includes a base unit 104 that is in wireless communication with one or more sensor units 102 and is optionally in wired or wireless communication with one or more devices 106. As described above, the sensor units may be directly coupled to the base unit, or may alternatively pass their data to the base unit indirectly, through a server, network, or other electronic device. The base unit 104 includes a processor 112, a user interface 114, local memory 116, and a communication component 120. The base unit 104 receives acceleration information wirelessly from each of the sensor units 102 and optionally makes that data available to the one or more additional devices 106.

In some versions, the base unit 104 or any of the devices 106 are in wired or wireless connection with a medical system 124 over a public or private data network 108. The medical system 124 receives acceleration, identification or other information from the base unit 104 or the devices 106 for analysis with regard to stored athlete information and/or storage into a database 126.

FIG. 9 is a perspective view of a mouth guard 400 formed in accordance with an example embodiment of the invention. The mouth guard 400 is an example of one of the types of sensor units 102 that may be used with the system 100 shown in FIG. 8. The mouth guard 400 defines a channel 402 for receiving a plurality of teeth of a user. In an example embodiment, the channel 402 is structured such that it covers teeth that include the incisors of a user when the mouthpiece is inserted. The mouth guard 400 also defines an open area 404 that allows the user's tongue to touch their upper palate after the mouth guard 400 has been inserted. This allows the user to maintain verbal communication with others without the additional effort required with other types of mouth guards having a solid portion that covers the upper palate.

The mouth guard 400 also includes a first battery 406 and a second battery 408. The batteries 406, 408 are electrically connected to a sensing module 410 and may be recharged with a wireless battery charger in some embodiments. In an example embodiment, the sensing module 410 is located at a front portion of the mouth guard 400 that covers the incisors of a user when the mouth guard 400 is inserted. However, the sensing module 410 may be located in a different area of the mouth guard in other embodiments. The sensing module 410 includes a three axis accelerometer 412 that senses acceleration along three orthogonal linear axes, a three axis gyroscope 414, and an electronics module 416 that are attached to a flex-printed circuit 418 (FPC) in an example embodiment. The accelerometer 412 preferably senses accelerations of at least 90 g and the gyroscope is preferably sensitive to at least 6000 degrees per second. In a preferred version, the electronic components described above are all positioned along an outer portion of the mouth guard where they will be located outside the teeth of the user and encapsulated within the material forming the mouth guard.

In accordance with preferred implementations of the invention, the accelerometer and gyroscope sense attributes of the environment of the mouth guard or other sensor unit 102 to determine a rate of acceleration of the sensor unit and an orientation of the sensor unit over time. Thus, by matching the acceleration and the position, the sensor unit is able to determine not only the fact of an event causing acceleration of a particular magnitude, but also a direction of the acceleration based on the direction of movement of the sensor unit. These data can be coupled, either in the sensor unit, the base unit, or another device, to calculate a vector representative of a combined direction and magnitude of the acceleration experienced by the sensor unit. In some instances the sensed event may be determined to be a straight line vector, while in other instances the motion of the sensor unit may be along an arc or otherwise rotational.

Although the sensing module 410 includes the three axis accelerometer 412 and the three axis gyroscope 414 in this embodiment, other sensor combinations may be used in other embodiments. For example, a two axis gyroscope in combination with a single axis gyroscope may be used rather than a three axis gyroscope, or additional linear accelerometers may be used rather than a gyroscope. In accordance with preferred implementations of the invention, however, the sensing module includes components that are capable of sensing both acceleration and position of the sensor unit.

A proximity sensor 420 is also in signal communication with the electronics module 416. The proximity sensor 420 includes a capacitive touch sensor in an example embodiment, but may include other types of sensors in other embodiments such as a temperature sensor or an optical sensor, for example. Most preferably, the proximity sensor is configured to indicate whether the mouth guard or other sensor unit is positioned in the player's mouth or otherwise engaged and in use. The sensing module 410 may also be configured as an application specific integrated circuit (ASIC) in some embodiments.

FIG. 10 is a diagram of the sensing module 410 showing additional detail for the electronics module 416 in accordance with an example embodiment of the invention. The electronics module 416 includes a processor 440 in data communication with a memory 442. The electronics module 416 also includes a transceiver 444 in signal communication with the processor 440.

In an example embodiment, the accelerometer block 412 includes three single axis accelerometers such as model AD22283 produced by Analog Devices, Inc. The gyroscope block 414 includes a dual axis sensor such as model LPR5150AL produced by STMicroelectronics and a single axis sensor such as model LY5150ALH produced by STMicroelectronics. The processor block 440 includes a microcontroller such as model MSP430F5522 produced by Texas Instruments, the memory block 442 includes a memory module such as model M25P32 produced by Numonyx, and the transceiver block 444 includes a transceiver such as model CC1101 produced by Texas Instruments in an example embodiment. However, different components may be used in other embodiments. For example, piezoelectric and/or piezoresistor based sensors may be used in some embodiments.

FIGS. 11-13 show additional views of the mouth guard 400 shown in FIG. 9. FIG. 11 is a top view of the mouth guard 400. FIG. 12 is a front view of the mouth guard 400. FIG. 13 is a side view of the mouth guard 400. As best seen in FIG. 11, the electronic components are positioned on an outer portion of the channel formed for receiving the teeth of the user.

FIG. 14 is a flowchart of a method 800 of producing a mouth guard having an encapsulated sensor module. First, at a block 802, a first sheet of ethylene vinyl acetate (EVA) is vacuum formed using a mold to produce a first mouth guard layer. Next, at a block 804, a sensor module is attached to the first mouth guard layer with an EVA based hot melt adhesive. In an example embodiment, the sensor module is configured in a similar manner to the sensing module 410 described with respect to FIGS. 9 and 10 and at least one battery such as the batteries 406, 408 and a proximity sensor such as sensor 420 are also attached to the first mouth guard layer. Then, at a block 806, a second sheet of EVA is vacuum formed over the sensor module to produce a second mouth guard layer. This encapsulates the sensor module, the battery, and the proximity sensor between the first and second mouth guard layers in an example embodiment.

In alternate versions of the invention, different molding techniques are used. Thus, for example, the sensors may be mounted in position while an injection molding process forms the mouth guard about the sensors and other components.

Next, at a block 808, a first default threshold level and a second default threshold level are stored in the sensor module. The default levels may be stored in a memory in data communication with a processor in the sensing module, for example as described above. The default levels are set such that the processor will instruct a transceiver to transmit a signal to a base unit if an accelerometer in the sensor module detects an acceleration greater than the first default level and will further instruct the transceiver to continue transmitting the signal if an acceleration greater than the second default level is detected during a predefined time period after the transceiver begins transmitting.

Next, at a block 810, the sensor module is calibrated to account for sensor alignment. Depending on the sensor used and the method of incorporation into the mouth guard, the sensors may or may not be perfectly oriented with the desired axes of alignment. In various versions of the invention, the mouth guard may include one or more sensors such as included within a module 410 that may include a three axis accelerometer 412 and gyroscope 414. Other versions may have different individual sensors, though in most preferred versions the sensors include an axial alignment to detect impacts along one or more specific axes. It is useful to be able to associate the axes of the sensors with those of the mouth guard for better measurement and analysis of the data. Accordingly, the mouth guard is preferably calibrated for alignment.

In one version, the calibration step includes use of a turntable mounted for rotation about a spindle or other central axis. The mouth guard is placed on the turntable in a known orientation. The turntable is then rotated at a known speed, thereby imparting centripetal forces on the mouth guard and sensors that can be detected as acceleration or g forces. A receiver can monitor the movement detected by the sensors and compare the detected vectors against the true vectors applied by the turntable in order to calibrate the mouth guard. The calibration adjustments may be recorded in a table in a computer or server as desired so that it can adjust sensed forces to account for the calibration. Alternatively, the embedded memory in the mouth guard may be programmed to store the calibration data for adjustment of sensed information locally at the mouth guard. Most preferably the mouth guard is calibrated in this fashion across three axes.

Although the steps above are described as occurring sequentially in a particular order, it should be understood that they may occur in a different order and that a subset of the steps or additional steps may be present in some embodiments. Additionally, enclosure of the sensor module in the mouth guard may be performed in another manner such as by attaching the sensor module to the second EVA sheet rather than to the first mouth guard layer and then vacuum forming the combined sheet and sensor module to the first mouth guard layer, for example.

While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. For example, although the mouth guard is described as being produced with sheets of EVA and an EVA based adhesive, other types of materials and adhesives may be used in other embodiments. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow. 

1. A method comprising: forming a first mouth guard layer; attaching a sensor module to the first mouth guard layer; and encapsulating the sensor module between the first mouth guard layer and a second mouth guard layer.
 2. The method of claim 1, wherein the first mouth guard layer is formed from ethylene vinyl acetate (EVA).
 3. The method of claim 2, wherein the step of attaching the sensor module to the first mouth guard layer is performed with an EVA based hot melt adhesive.
 4. The method of claim 1, further comprising storing a first default threshold level in the sensor module.
 5. The method of claim 4, further comprising storing a second default threshold level in the sensor module.
 6. The method of claim 1, further comprising calibrating the sensor module to account for sensor alignment after the sensor module is encapsulated.
 7. The method of claim 6, wherein the step of calibration comprises mounting the mouth guard on a turntable, rotating the turntable, and recording information from the sensor module.
 8. The method of claim 1, further comprising attaching a battery to the first mouth guard layer, wherein the battery is also encapsulated between the first and second mouth guard layers.
 9. The method of claim 1, wherein the first and second layers are formed such that they define an open area that allows a user's tongue to touch an upper palate of the user after the mouth guard has been inserted.
 10. The method of claim 1, wherein the first and second layers are formed such that they define a channel for accepting a plurality of teeth, including the incisors of a user.
 11. The method of claim 1, further comprising attaching a proximity sensor to the first mouth guard layer, the proximity sensor also being encapsulated between the first and second mouth guard layers.
 12. The method of claim 1, wherein the first layer is formed by injection molding.
 13. The method of claim 12, wherein the step of attaching the sensor module and the step of encapsulating the sensor module are performed substantially simultaneously with the step of forming the first layer by injection molding. 